To satisfy demands for wireless data traffic having increased since commercialization of 4th-Generation (4G) communication systems, efforts have been made to develop improved 5th-Generation (5G) communication systems or pre-5G communication systems. For this reason, the 5G communication system or the pre-5G communication system is also called a beyond-4G-network communication system or a post-Long Term Evolution (LTE) system.
To achieve a high data rate, implementation of the 5G communication system in an ultra-high frequency (mmWave) band (e.g., a 60 GHz band) is under consideration. In the 5G communication system, beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), an array antenna, analog beamforming, and large-scale antenna technologies have been discussed to alleviate a propagation path loss and to increase a propagation distance in the ultra-high frequency band.
For system network improvement, in the 5G communication system, techniques such as an evolved small cell, an advanced small cell, a cloud radio access network (RAN), an ultra-dense network, a device to device (D2D) communication, a wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMPs), and interference cancellation have been developed.
In the 5G system, advanced coding modulation (ACM) schemes including hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC), and advanced access schemes including filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed.
Internet, which is a human-oriented connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information. The Internet of Everything (IoE) has also emerged, which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server.
As technology elements, such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology, have been demanded for IoT implementation, a sensor network, a Machine to Machine (M2M), Machine Type Communication (MTC), and so forth have been recently researched for connection between things.
Such an IoT environment may provide intelligent Internet technology (IT) services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances, advanced medical services, and so forth through convergence and combination between existing IT and various industries.
Thus, various attempts have been made to apply 5G communication systems to IoT networks. For example, 5G communication technologies such as sensor networks, things communication, MTC, etc., have been implemented by schemes such as beamforming, MIMO, array antennas, and so forth. Application of the cloud RAN as the Big Data Processing technology may also be an example of convergence of the 5G technology and the IoT technology.
Meanwhile, one of methods for satisfying high traffic demands in a communication system is to use a broad frequency bandwidth. In frequencies used in most communication systems (i.e., frequencies less than 5 GHz), a broad frequency bandwidth is difficult to secure, such that a frequency bandwidth needs to be secured among high frequencies. The Institute of Electrical and Electronics Engineers (IEEE) 802.11ad is the standard for providing a high data rate of several giga bits per second by using a broad frequency bandwidth in a 60 GHz band.
Channel estimation in IEEE 802.11ad is performed in a channel estimation field (CEF) period in a transmission packet, and a Golay code is used as a pilot for the channel estimation. The Golay code is a binary sequence including +1 and −1, and two sequences form one pair. By using characteristics of correlation of a Golay code pair, a channel may be estimated.
However, the current IEEE 802.11ad standard has been designed based on a single-input single-output (SISO) system, but has been determined to be extended to a multiple-input multiple-output (MIMO) system in the future pre-5G or post-11ad standard. To enable MIMO transmission in a pre-5G or post-11ad system, a scheme for efficiently estimating a channel in the MIMO system is required.